specium

Specium provides the inverse function of clojure.spec(.alpha)/form, reducing eval calls as much as possible.

Installation

Add the following to your :dependencies:

Usage

A common way of getting a s/formed spec form back into a spec object is to call eval with it:

=> (s/form (s/map-of keyword? integer?))
(clojure.spec.alpha/map-of clojure.core/keyword? clojure.core/integer?)
=> (eval *1)
#object[clojure.spec.alpha$every_impl$reify__946 0x6d47d0b2 "clojure.spec.alpha$every_impl$reify__946@6d47d0b2"]
=> (s/conform *1 {:key "wrong value"})
:clojure.spec.alpha/invalid
=> (s/explain *2 {:key "wrong value"})
In: [:key 1] val: "wrong value" fails at: [1] predicate: integer?
:clojure.spec.alpha/spec  #object[clojure.spec.alpha$every_impl$reify__946 0x6d47d0b2 "clojure.spec.alpha$every_impl$reify__946@6d47d0b2"]
:clojure.spec.alpha/value  {:key "wrong value"}
nil
=> 

Though it perfectly works, in some cases you might not be able to overlook eval's inefficiency (eg. where lots of spec forms have to be dealt with).

Specium provides the ->spec fn, which can be used as the inverse function of s/form; that is, you can use it to get spec forms back to spec objects efficiently, almost without calling eval:

=> (require '[specium.core :as specium])
nil
=> (s/form (s/map-of keyword? integer?))
(clojure.spec.alpha/map-of clojure.core/keyword? clojure.core/integer?)
=> (def s (specium/->spec *1))
#'user/s
=> (s/conform s {:key "wrong value"})
:clojure.spec.alpha/invalid
=> (s/explain s {:key "wrong value"})
In: [:key 1] val: "wrong value" fails at: [1] predicate: integer?
:clojure.spec.alpha/spec  #object[clojure.spec.alpha$every_impl$reify__946 0x581fa0b "clojure.spec.alpha$every_impl$reify__946@581fa0b"]
:clojure.spec.alpha/value  {:key "wrong value"}
nil
=>

Note that we said "almost without calling eval", which means that eval is actually necessary in some cases, especially in the case the spec form has an fn form in it as a predicate.

License

Copyright © 2017 Shogo Ohta

Distributed under the Eclipse Public License either version 1.0 or (at your option) any later version.